Heretofore, technologies for determining molecule structures of molecules have become available. There is also a related technology for a method that assigns a molecular force field to a molecule. According to the technology, a bond type representing the type of bond between atoms is determined depending on whether or not the bond distance between atoms which is calculated using quantum-mechanical-calculation called a molecular orbital method exceeds a predetermined threshold (For example, see International Publication Pamphlet No. WO 2008/041304).
According to the related art, however, it is difficult to assign an appropriate molecular force field to a molecule. For example, when the bond type is determined based on the bond distance between atoms, the difference in the bond distance between the atoms, the difference being caused by a difference in the bond type, is small. Thus, when the calculation accuracy of the quantum-mechanical-calculation is low, there are cases in which an erroneous bond type is determined and the erroneous bond type may cause assignment of an erroneous molecular force field.